1. Field of the Invention
The present invention generally relates to a removable unit and an image forming apparatus, such as a copier, a printer, a facsimile machine, or a multifunction machine including at least two of these functions, that includes a unit removably mounted in the apparatus.
2. Description of the Related Art
In image forming apparatuses, such as copiers and printers, there is an increasing demand for forming images on both sides of sheets of recording media (i.e., double-side printing or duplex printing) to save natural resources and become eco-friendly. At present, many compact image forming apparatuses, which are generally low-speed apparatuses, also have a conveyance unit for duplex printing (i.e., a reversal conveyance unit). On the other hand, there still is a certain demand for omitting the conveyance unit for duplex printing to keep the apparatus compact and save costs.
In view of the foregoing, optional conveyance, units for duplex printing retrofitted to a lateral side or rear side of the image forming apparatus have been proposed. Such conveyance units or feed units (hereinafter also “modular units”) are removably mounted to an apparatus body and typically include a cover that is opened to expose an interior of the unit for removal of jammed sheets or maintenance work. Accordingly, before use, it is necessary to confirm whether the cover is closed and the removable module unit is mounted to the apparatus body properly.
For example, JP-2009-073582-A proposes a duplex conveyance unit that includes a cover to expose a top of the duplex conveyance unit, a planar feeler attached to the cover, and a detector in which a detection slit is formed. When the duplex conveyance unit is mounted to the apparatus body with the cover closed, the planar feeler fits in the detection slit, with which the detector deems that the duplex conveyance unit is mounted to the apparatus body and the cover is closed.
In this configuration, however, the detection slit is relatively narrow, and it is necessary that the planar feeler and the detection slit be precisely positioned relative to each other to confirm whether the duplex conveyance unit is properly mounted to the apparatus body with the cover closed.